The difference would be negligible.
The the_content filter is fired regardless of whether you use it or not because WordPress uses it for other things. So the only thing that would be performance related would be the complexity of your filter function.
But since you’d probably be doing the same level of complexity in a template or in the filter function, there’s no real difference between the two.
I would say that you’d be better using the filter if you want the table to be part of the main content area. Then you don’t have to worry as much about how/what styles are applied.